Vaidyanathan, G., Affleck, D.J., Bigner, D.D. & Zalutsky, M.R. N-succinimidyl 3-[211At]astato-4-guanidinomethylbenzoate: an acylation agent for labeling internalizing antibodies with alpha-particle emitting 211At. Nucl. Med. Biol. 30, 351-359

Department of Biomedical Engineering (BME), Duke University, Durham, North Carolina, United States
Nuclear Medicine and Biology (Impact Factor: 2.41). 06/2003; 30(4):351-9. DOI: 10.1016/S0969-8051(03)00005-2
Source: PubMed


The objective of this study was to develop a method for labeling internalizing monoclonal antibodies (mAbs) such as those reactive to the anti-epidermal growth factor receptor variant III (EGFRvIII) with the alpha-particle emitting radionuclide (211)At. Based on previous work utilizing the guanidine-containing acylation agent, N-succinimidyl 4-guanidinomethyl-3-[(131)I]iodobenzoate ([(131)I]SGMIB), we have now investigated the potential utility of its astato analogue for labeling the anti-EGFRvIII mAb L8A4. N-succinimidyl 3-[(211)At]astato-4-guanidinomethylbenzoate ([(211)At]SAGMB) in its Boc-protected form was prepared from a tin precursor in 61.7 +/- 13.1% radiochemical yield, in situ deprotected to [(211)At]SAGMB, which was coupled to L8A4 in 36.1 +/- 1.9% yield. Paired-label internalization assays demonstrated that tumor cell retention of radioactivity for L8A4 labeled using [(211)At]SAGMB was almost identical to L8A4 labeled using [(131)I]SGMIB, and 3-4-fold higher than for mAb radioiodinated using Iodogen. Paired-label biodistribution of L8A4 labeled using [(211)At]SAGMB and [(131)I]SGMIB in athymic mice hosting U87MGdeltaEGFR xenografts resulted in identical uptake of both (211)At and (131)I in tumor tissues over 24 h. Although higher levels of (211)At compared with (131)I were sometimes seen in tissues known to sequester free astatide, these (211)At/(131)I uptake ratios were considerably lower than those seen with other labeling methods. These results suggest that [(211)At]SAGMB may be a useful acylation agent for labeling internalizing mAbs with (211)At.

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Available from: Michael Zalutsky, Nov 05, 2015
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    • "different ways (Wilbur et al., 2007; Pruszynski et al., 2006, 2008; Vaidyanathan et al., 2003). Coupling a stannylated aromatic succinimide ester, MeATE reagent, via N-acylation reactions with lysine on the biomolecule, followed or preceded by an electrophilic aromatic substitution of Sn(CH 3 ) 3 with 211 At is, although, the most common method (Zalutsky and Narula, 1988; Lindegren et al., 2008). "
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    ABSTRACT: In this work a new coupling reagent, N-[2-(maleimido)ethyl]-3-(trimethylstannyl)benzamide, for radiohalogenation has been synthesized and characterized. The reagent is intended to either be attached to reduced disulfide bridges of proteins (making the halogenation site-specific) or to free terminal cysteine groups on peptides. The new reagent was also shown to be easily halogenated with inactive bromine and iodine as well as (125)I and (211)At, indicating potential use within targeted radiotherapy. Copyright © 2014 Elsevier Ltd. All rights reserved.
    Applied Radiation and Isotopes 11/2014; 96C:1-5. DOI:10.1016/j.apradiso.2014.11.007 · 1.23 Impact Factor
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    • "considered. Indirect radiolabeling mainly uses the electrophilic substitution of leaving groups attached to vinylic [8] or aromatic backbones [9] [10] [11] with At(+ I). Accordingly, succinimidyl astatobenzoate (SAB), which is currently the most frequently used for proteins labeling with astatine-211, is synthesized from the halodemetalation of a stannylated aromatic precursor [12]. "
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    ABSTRACT: Introduction The clinical development of radioimmunotherapy with astatine-211 is limited by the lack of a stable radiolabeling method for antibody fragments. An astatinated N-heterocyclic carbene (NHC) Rhodium complex was assessed for the improvement of radiolabeling methodologies with astatine. Methods Wet harvested astatine-211 in diisopropyl ether was used. Astatine was first reduced with cysteine then was reacted with a chlorinated Rh-NHC precursor to allow the formation of the astatinated analogue. Reaction conditions have been optimized. Astatine and iodine reactivity were also compared. Serum stability of the astatinated complex has been evaluated. Results Quantitative formation of astatide was observed when cysteine amounts higher than 46.2 nmol/μl of astatine solution were added. Nucleophilic substitution kinetics showed that high radiolabeling yields were obtained within 15 min at 60 °C (88%) or within 5 min at 100 ° C (95%). Chromatographic characteristics of this new astatinated compound have been correlated with the cold iodinated analog ones. The radioiodinated complex was also synthesized from the same precursor (5 min. at 100 °C, up to 85%) using [125I]NaI as a radiotracer. In vitro stability of the astatinated complex was controlled after 15 h. incubation in human serum at 4 °C and 37 °C. No degradation was observed, indicating the good chemical and enzymatic stability. Conclusion The astatinated complex was obtained in good yield and exhibits good chemical and enzymatic stability. These preliminary results demonstrate the interest of this new radiolabeling methodology and further functionalizations should open new possibilities in astatine chemistry. Advances in Knowledge and Implications for patient Care Although there are many steps and pitfalls before clinical use for a new prosthetic group from the family of NHC complexes, this work may open a new path for astatine-211 targeting.
    Nuclear Medicine and Biology 01/2013; 41. DOI:10.1016/j.nucmedbio.2013.12.004 · 2.41 Impact Factor
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    • "We have developed a template for the radiohalogenation of mAbs that undergo receptor-mediated internalization and mAbs labeled with this reagent have shown encouraging enhancement of tumor radioactivity residence time [27] [28] [29]. Because octreotide derivatives also undergo receptor-mediated internalization, our objective was to develop an octreotate conjugate comprising this template. "
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    ABSTRACT: Derivatives of the somatostatin analogues octreotide and octreotate labeled with radioiosotopes are used in the diagnosis and therapy of somatostatin receptor (SSTR)-positive tumors. A method has been devised to synthesize {N-(4-guanidinomethyl-3-iodobenzoyl)-Phe1-octreotate (GMIBO). Receptor binding assay and scatchard analysis yielded a Kd of 4.83 +/- 0.19 nM for this peptide. Derivatives of this peptide labeled with radioiodine ([*I]GMIBO) and the alpha-particle-emitting radiohalogen 211At N-(3-[211At]astato-4-guanidinomethylbenzoyl)-Phe1-octreotate; [211At]AGMBO} were prepared in a single step from a tin precursor in radiochemical yields of 30-35% and 15-20%, respectively. Paired-label internalization assays performed with the SSTR-positive D341 Med human medulloblastoma cell line demonstrated that [125I]GMIBO and [211At]AGMBO were specifically internalized 20-40% more than Nalpha-(1-deoxy-D-fructosyl)-[131I]I-Tyr3-octreotate ([131I]I-Glu-TOCA), the radioiodinated octreotide derivative previously shown to exhibit maximum internalization in this cell line. Uptake of [131I]GMIBO in D341 Med subcutaneous xenografts in a murine model (8.34 +/- 1.82 versus 8.10 +/- 2.23% ID/g at 1h) and SSTR-expressing normal tissues was comparable to that of [125I]I-Glu-TOCA and was shown to be specific. However, the uptake of [131I]GMIBO also was substantially higher in liver (16.9 +/- 3.15 versus 1.39 +/- 0.45% ID/g at 1 h) and in kidneys (44.33 +/- 6.47 versus 3.44 +/- 0.68% ID/g at 1h) compared to that of [125I]I-Glu-TOCA. These data suggest that these novel peptide conjugates retain their specificity for SSTR both in vitro and in vivo; however, because of their higher accumulation in normal tissues they would be best applied in settings amenable to loco-regional administration such as medulloblastoma neoplastic meningitis.
    Peptides 01/2005; 25(12):2087-97. DOI:10.1016/j.peptides.2004.08.018 · 2.62 Impact Factor
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